// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#ifndef B2_WELD_JOINT_H
#define B2_WELD_JOINT_H

#include "b2_api.h"
#include "b2_joint.h"

/// Weld joint definition. You need to specify local anchor points
/// where they are attached and the relative body angle. The position
/// of the anchor points is important for computing the reaction torque.
struct B2_API b2WeldJointDef : public b2JointDef
{
  b2WeldJointDef()
  {
    type = e_weldJoint;
    localAnchorA.Set(0.0f, 0.0f);
    localAnchorB.Set(0.0f, 0.0f);
    referenceAngle = 0.0f;
    stiffness = 0.0f;
    damping = 0.0f;
  }

  /// Initialize the bodies, anchors, reference angle, stiffness, and damping.
  /// @param bodyA the first body connected by this joint
  /// @param bodyB the second body connected by this joint
  /// @param anchor the point of connection in world coordinates
  void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);

  /// The local anchor point relative to bodyA's origin.
  b2Vec2 localAnchorA;

  /// The local anchor point relative to bodyB's origin.
  b2Vec2 localAnchorB;

  /// The bodyB angle minus bodyA angle in the reference state (radians).
  float referenceAngle;

  /// The rotational stiffness in N*m
  /// Disable softness with a value of 0
  float stiffness;

  /// The rotational damping in N*m*s
  float damping;
};

/// A weld joint essentially glues two bodies together. A weld joint may
/// distort somewhat because the island constraint solver is approximate.
class B2_API b2WeldJoint : public b2Joint
{
public:
  b2Vec2 GetAnchorA() const override;
  b2Vec2 GetAnchorB() const override;

  b2Vec2 GetReactionForce(float inv_dt) const override;
  float GetReactionTorque(float inv_dt) const override;

  /// The local anchor point relative to bodyA's origin.
  const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }

  /// The local anchor point relative to bodyB's origin.
  const b2Vec2& GetLocalAnchorB() const  { return m_localAnchorB; }

  /// Get the reference angle.
  float GetReferenceAngle() const { return m_referenceAngle; }

  /// Set/get stiffness in N*m
  void SetStiffness(float hz) { m_stiffness = hz; }
  float GetStiffness() const { return m_stiffness; }

  /// Set/get damping in N*m*s
  void SetDamping(float damping) { m_damping = damping; }
  float GetDamping() const { return m_damping; }

  /// Dump to b2Log
  void Dump() override;

protected:

  friend class b2Joint;

  b2WeldJoint(const b2WeldJointDef* def);

  void InitVelocityConstraints(const b2SolverData& data) override;
  void SolveVelocityConstraints(const b2SolverData& data) override;
  bool SolvePositionConstraints(const b2SolverData& data) override;

  float m_stiffness;
  float m_damping;
  float m_bias;

  // Solver shared
  b2Vec2 m_localAnchorA;
  b2Vec2 m_localAnchorB;
  float m_referenceAngle;
  float m_gamma;
  b2Vec3 m_impulse;

  // Solver temp
  int32 m_indexA;
  int32 m_indexB;
  b2Vec2 m_rA;
  b2Vec2 m_rB;
  b2Vec2 m_localCenterA;
  b2Vec2 m_localCenterB;
  float m_invMassA;
  float m_invMassB;
  float m_invIA;
  float m_invIB;
  b2Mat33 m_mass;
};

#endif
